1. Field of the Invention
The present invention relates to a programmable logic device in which a connection state can be kept even while power is not supplied.
2. Description of the Related Art
Since a design of a logic circuit in a programmable logic device (PLD) can be changed by a user after the PLD is released on the market, the PLD is used in a variety of products from a prototype to a mass-produced product.
A field programmable gate array (FPGA) is a typical PLD. The FPGA includes a plurality of logic circuits, and on and off of a switch which changes a connection state of the logic circuits are controlled in accordance with data (configuration data) stored in a memory portion. Thus, a logic state of the FPGA can be changed even after its manufacture.
In recent years, a programmable logic device in which a connection state of logic circuits can be kept even while power supply voltage is not supplied has been actively researched and developed (e.g., Patent Document 1).